1. Field of the Invention:
The present invention relates to a process for producing finely-divided particulate bismuth oxide from bismuth.
2. Description of the Prior Art:
Among the conventional processes for producing finely-divided particulate bismuth oxide are:
(1) a wet process in which an alkali is added to an aqueous solution of bismuth nitrate or chloride to form precipitates of bismuth subnitrate or bismuth hydroxide, and the precipitates are subsequently separated from the mother liquor, followed by calcination; and
(2) a dry process in which bismuth is compulsorily oxidized in an electric furnace and the vaporized bismuth oxide is collected.
The first process has a disadvantage that the product contains alkali metal and nitrate groups and is rather coarse in particle diameter (2 to 10 .mu.m). The second process also has a disadvantage that the product has a large particle diameter (5 to 10 .mu.m) although it contains no impurities.